In Advanced Television Systems Committee (ATSC) 8-VSB receiver, many efforts have been made to improve the performance of an RF front end and a synchronization and channel equalizer in association with a fixed reception (RX) channel. However, the performance of a fixed-channel receiver is greatly degraded by introduction of multipath waves in a dynamic multipath channel such as a mobile RX channel.
Therefore, the development of the diversity receiver having the improved mobile reception performance of the ATSC 8-VSB receiver is essential for a single frequency network system as well as a multi frequency network. For this purpose, signal selection schemes for obtaining an optimal single demodulation signal in a multi demodulator must be continuously studied.
That is, the selection of the optimal single demodulation signal is very important in the diversity receiver used for improving the mobile reception performance of the ATSC 8-VSB.
The ideal method for selecting a candidate signal having the optimal reception performance is to demodulate, equalize and channel-decode all RX signals and select an optimal baseband signal from the processed RX signals. However, because this method uses N separate receivers, its implementation is complex.
According to the related art, an optimal signal is selected using strength of the diversity antenna output signal power or information on channel response characteristic. However, because the method using the intensity of the RX signal power selects the optimal signal without considering the channel response characteristic, the performance of the DTV receiver is not greatly improved.
Meanwhile, an optimal signal can be selected according to signal-to-noise ratio (SNR) by measuring channel response characteristic. This method selects an optimal signal by calculating correlation values of a RX signal and a training sequence. That is, this method selects a signal having highest channel improvement in the receiver side.
The two conventional methods are applied to the diversity multi-demodulation receiver using a single equalizer. However, when the channel changes abruptly, an image cut-off phenomenon may be caused by a field sync signal and a re-convergence of an equalizer.
Therefore, there is a demand for an optimal signal selecting algorithm that can obtain high reception performance from a plurality of baseband signals received through a diversity antenna, and a receiver using the same.